Right angle drives, such as generally exemplified in U.S. Pat. No. 2,620,840, are commonly used in rotary power drill applications to convert the axis of rotation by 90 degrees. Right angle drives are useful in a number of situations where it is difficult to orient or manipulate the drill into alignment with the working surface or where impediments make it hard for the drill to reach the desired location. Such right angle drives are relatively simple in construction and can be readily used with all or most commercially available rotary drills. Right angle drives can be readily attached and detached from the chucks of rotary drills to allow for quick adaptation of the drill. The problem with right angle drives is that the angle of such drives are fixed at 90 degrees. Either a workman can drill at a straight angle (0 degrees) or the workman can drill at a right angle (90 degrees), but not angles therebetween. Although right angle drives increase the ergonomics of drills by providing an additional angular drilling option, the problem with right angle drives is that they are still limited in that a workman only has two fixed angles to select between which insufficient and undesirable for many hard to reach spots or impediments. There are many drilling applications in which various intermediate angles of between 0 and 90 degrees would be beneficial.
An attempt at an adjustable power transmitting device for a drill is disclosed in Grech, U.S. Pat. No. 4,332,147 (Re. 32,415). To Applicant's knowledge, this device has not met with commercial acceptance and is not commercially available. There appears to be several drawbacks and impracticalities related to this disclosed device. Most notably, this device appears to require fastening of the device to the drill body. Thus, the device would not appear to be readily usable with many commercially available drills and in fact would be limited to only drills having suitable mounting capabilities. Several other drawbacks and problems with Grech will become readily apparent with an appreciation of the various aspects of Applicant's invention.